One means for increasing the performance of an internal combustion engine is to increase the volume of air supplied to the combustion chambers thereof. Superchargers are one well known means for accomplishing this. Superchargers compress an incoming air charge and supply it to the combustion chambers of the engine. The resultant air charge supplied to the engine has a higher density, resulting in greater power output upon combustion.
Typically, superchargers are positioned at the end of the engine, below the engine, or on top of the intake manifold above the engine. Each of these configurations greatly increases the overall profile of the engine. For example, if the supercharger is positioned at the front or rear ends of the engine, the overall length of the engine is increased. This is generally unacceptable when the engine is mounted in transverse fashion within an automobile engine compartment or in an outboard motor cowling, as the length of the engine may exceed the maximum length of the compartment.
The supercharger may also be placed below the engine, but this has the disadvantage of increasing the "height" of the engine, and requires long air runners extending from the supercharger around the engine to the intake passages leading through the engine to the combustion chambers.
Lastly, it is known to position the supercharger on top of the intake manifold above the engine, as illustrated in FIGS. 1(a) and 1(b). As illustrated in FIG. 1(a), a supercharger 248 may be mounted above an intake manifold 266 having runners 270 extending therefrom. The runners 270 extend to intake passages 272 leading through a cylinder head 228, 230 connected to the block 222 of the engine.
This arrangement suffers from the fact that the supercharger 248 extends a great distance "H" beyond the engine, increasing the total engine profile dramatically. Another problem is that the manifold 266 and runners 272 are positioned adjacent the engine, such that the engine heat causes an increase in the temperature of the air flowing therethrough, reducing the efficiency of the engine and negating much of the benefits of the supercharger (thus often necessitating the use of an intercooler as well). Also, because the supercharger 248 is positioned a great distance from the engine, it may require a long drive belt extending from the engine crankshaft to the supercharger drive. The length of the belt and its orientation may reduce the longevity of the belt.
One attempt at reducing the problems associated with the above-stated prior art arrangement is illustrated in FIG. 1(b). As illustrated therein, the manifold 266 and its runners 270 have a number of bends, thereby reducing the total distance by which the supercharger 248 extends beyond the engine to a height H' (H' being less than H). Still, however, the supercharger 248 extends well beyond the engine. In addition, the intake manifold 266 and runners 270 are positioned even closer to the engine, and further, the resistive losses are increased by the air's travelling through the curvaceous intake passages.
A "V"-type engine which is supercharged and has its supercharger arranged so that the increase in engine profile is minimized is desired.